Typescript method decorator with args

unsubscribe.ts

/**
 * Decorator to ensure widgets unsubscribe and clean up subscriptions on each new subscription.
 */
export function Unsubscribe<T>(): Function {

  return function(targetClass, functionName: string, descriptor): Function {
    const source = descriptor.value;

    descriptor.value = function(...args): void {

      if (this.dataSubscription) {
        this.dataSubscription.unsubscribe();
      }
      return source.apply(this, args);
  }

  return descriptor;
  };
}